This invention relates to an exercise machine.
Exercise machines make use of diverse devices such as free weights, weight plates, elastic bands, springs and the like to provide a resistance force against which a user can exercise. It has been found that, in many of these machines, the stroke length, which is the distance against which a user moves his arms or legs, as the case may be, against a resistive force, must be reasonably long and this, in turn, means that an exercise machine must also be of substantial dimensions.
It is preferable to have a substantially constant resistance force, against which a user exercises, over the stroke length. If use is made of a spring or similar component, to provide the resistance force then, as is known, the spring characteristic is such that the resistance force increases more or less linearly with spring deformation. In other words the more the resistance device is moved the greater is the resistance force which acts against movement from the user. This is not necessarily a desirable characteristic.
If one or more weights are used to provide the resistance force then a substantially constant resistance force is obtained over the stroke length. When a user who is physically strong makes use of the exercise machine then the number of weights which must be provided is substantial and this carries with it a penalty in that the exercise machine is then not necessarily easily transportable and, inevitably, the exercise machine is cumbersome and expensive to ship to a customer.
Another factor is that the positive resistance force, which is the resistance force displayed by the resistance device when energy is put into an exercise machine by a user, should, as far as is possible, be the same as the negative resistance force which results when energy which is stored in the exercise machine is released, on a return stroke. These forces can only be matched to one another, at least to some extent, if frictional and similar losses are minimised.
It should be possible, particularly for a device which is intended for a home user, to be able to adjust the resistance force, exhibited by an exercise machine, with relative ease. The exercise machine should, as noted, be compact and light so that it is suited for easy transport and storage, particularly for the home user. It is also desirable to be able to use the machine in one of at least two modes eg. by working against a resistance force by pulling downwardly on an actuator which may be of any suitable form eg. a handle, a bar, an ankle or wrist cuff, or the like, or by working against a resistance force by pulling upwardly on an actuator. These modes are given merely by way of example for the exercise machine could be constructed to provide the resistance force against other types of movement eg. a pushing or a rotating movement by the user.